7 ' I t E JIO I' K N .A I, O F I N I1 U S 1'KI A I, 21 .VI> B N G l N E E K I N C C I I t i ' M I S T K Y
Oct., 1'ii7
sensitivc fiber than Treatment 4 anti iricr alkali sensitivciiess to h,'s 50. U E T E K M I S A T I o N
.a,.xa
971
C o n t r a r y t o our expectations, however, the Congo Rcil viscosc silk fibers were found t o he altogctlier too sciisitivc t o t l i e organic acids t o be used as a means tinting organic from mineral acids. A Ier of organic acids were tested a n d t h e greater proportion of t h e m gave a positive color change in the Congo Red fiber in concentrations ranging from I g. to o . I g. per liter. The mineral acids give this color change in concentrations as low as 0 . 0 1 g. j x r litcr. S U >I M A R Y
i ~~Amethod for t h e detection of alkalinity and :icidily in minute drops of liquirl has been described. I I ~ 'The litmus silk fihcrs can he used for t.he dether acid or alkali, while the Congo R e d iihers can bc used [or the detection of
I I l ~ Acidity
iici... . . . . . . . . . . . ii..so,,. . . . . . . . . . . . . . . . . . .
S l I r O € S . . ..
...........
wiiino v/wm v,300
NaOH.. . . . . . . . . . . . . . . . . N:300 KO11 . . . . . . . . . . . . . . . Si300
5 .5 IS
BO
011
I20
7'nhlc I11 shows t h a t purified silk cannot, h c very satisfactorily d y e d in alkaline or neutral solution, hut can lx in i i concentrated acid soiution of litmus.
diic to mincral acids can he detected in ingly i l i l u t e solutions. it N i 4 j o o solution giving ii positive reaction. T h e indicator fihers are not iiiiitc so sciisit.ive t o alkali. IT? The sensitiveness of these indicator fibers varies with the degree of adsorption of the d y e , t h e v e e of purific:ition of thc m \ v silk and tlie degree of purification of the litmus. ' I ~ Congo ~ R c d fibers ciinnot h e used to differentiat,e organic ;icids f r o m mineral iicids.
I.*ecixrvwen iiltcr papers. was i ~ l u t i it~o yicltl :in eminently
llic.
iiii
M,caoscul.v N. Y.
l?,,AC.,.
10
20 2
II..--TKE DETECTION OF ACSDITY B Y M E A N S OF FIBERS DYED WSTK CONGO R E D I _
CIIC\IIC*I.
I:NI"IIHsITY.
A NEW ILLUMINATOR FOR MICROSCOPES' B Y AI.*I*III,EX
S,,.vzrMnN
T h e w hiis. for many years, been a demand for a satisfactory and convenient source of illuminatiun for
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
972
amined by chemists, biologists and metallographers a n d pronounced satisfactory for both direct observation and microphotography, i t is described here for those who may be interested. A s shown in t h e accompanying illustration, a small circular tube-lamp surrounds t h e objective a n d is attached t o a holder which is clamped t o t h e microscope tube. The design of both clamp and holder may be modified t o fit a binocular microscope. For t h e present, t h e holder illustrated is used because of t h e variation in diameter and shape of objectives. The lamp shown is a 6-volt tungsten lamp operated by six dry cells. Modffications of t h e l a m p are possible. The present one might be replaced by a nitrogenfilled tungsten, daylight tungsten, mercury or carbon dioxide lamp. The advantages in t h e use of. t h e new device lie in t h e fact t h a t a n object is illuminated b y a circular source of light, so directed by t h e reflector on t h e upper wall of t h e tube t h a t diffusion results. F u r t h e r , t h e light is always in place a n d is raised a n d lowered with t h e microscope tube, thus obviating t h e necessity for readjustment experienced in using vertical illuminators. T h e lamp, fitting snugly about t h e objective, enables one t o lower t h e light into hollow objects too deep t o permit of t h e use of a vertical illuminator. I n microphotography the lamp has been used t o good advantage. Satisfactory results have been obtained on specimens with a 5 mm. eyepiece and 8 , 16 and 3 2 mm. objectives. It has heretofore been quite difficult t o obtain good photographs in metallography with low-power objectives using older forms of illuminators. With the new illuminator excellent results were obtained. The time of exposure was, on a n average, 6 minutes for t h e 8. mm., 2'/2 minutes for t h e 16 mm., and I ' / ~minutes for t h e 3 2 mm. objective.
intake
B-3-way
stop cock as !n standard
OF P I T T S B U R G H PITTSBURGH. PA.
A NEW MODEL OF THE BURRELL AND OBERFELL APPARATUS FOR THE ANALYSIS OF ILLUMINATING GAS R . S U Y D A M , JR.
Received May 21, 1917
The apparatus shown herewith is practically identical with t h e apparatus described by Burrell and Oberfell in THIS J O U R N A L for March, 1916, page 2 2 8 , except t h a t i t has been p u t in a more compact stand which gives more protection t o t h e glass parts t h a n t h a t shown by t h e above writers, and t h a t a silica t u b e has been substituted for t h e glass one used by t h e m as a container for t h e copper oxide. The silica tube, which was made by t h e Hanovia Chemical Company of Newark, N . J., was more t h a n paid for by t h e saving of t h e expense for repairing t h e glass tube, which broke very frequently. The procedure for t h e analysis is identical with t h a t given by Burrell and Oberfell. The apparatus has given excellent results and is recommended as being more satisfactory for t h e
IO
Orsat apparafus
stap cock a5 in Burrell and Oberfell apparatus for opening the rneasunng burette, either t o the , i - - -L --absorption pipettes or the compensator ,
c-2-Wdy
-*.
I
sed Silica Tube
to
Bank I
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i.
analysis of illuminating gas t h a n t h e standard forms of apparatus now on t h e market. DEPARTMENT OF C H E X I C A L
SCHOOL OF CHEMISTRY UNIVERSITY
B y J.
/,-Sample
Vol. 9, No.
ENGIKEERING
COLUMBIA UNIVERSITY, N E W YORK CITY
A USEFUL DISTILLING HEAD By ORLO STEARNS Received May 28, 1915
The accompanying drawing explains t h e constr uction of a useful distilling head. The angle between h and i should be about 110'. This head was specially designed for and found exceptionally efficient in distilling troublesome fluid extracts. Such liquids often give rise t o a good deal of froth which carries some of t h e liquid along a n d renders redistillation necessary. Sometimes, however, t h e liquid is forced u p by spurts, or again rises in a body passing into t h e apparatus connected with t h e flask. I n t h e first instance t h e part of t h e head t h a t does t h e most service is t h e lobes fJ' in which t h e bubbles readily break by expansion a n d condensation. Bubbles often broke in passing the circular edge g,g' a t t h e lower end of t h e conical branch of t h e connecting tube, while t h e larger opening, across g,g', is less favorable for the entrance of bubbles t h a n a smaller one. T h e opening e in t h e lower part of bulb is directly over t h e drainage hole c a n d t h e re-
